Certain, probable, unlikely and impossible

Concepts with Marbles

Certain:

• Explanation: “This will definitely happen. It’s like if I put a red marble in the bag and tell you there’s a red marble in the bag, you know you will get a red marble if you pick one out.”
• Activity: Put a red marble in the bag and show it to them. Say, “If we pick a marble, we will always get a red marble. It’s certain!”

Probable:

• Explanation: “This is likely to happen but not for sure. It’s like if there are mostly red marbles in the bag and just a few blue ones, you will probably get a red marble.”
• Activity: Put a lot of red marbles and just a few blue marbles in the bag. Tell them, “If we pick a marble, we are more likely to get a red marble.”

Unlikely:

• Explanation: “This might happen but it’s not very likely. It’s like if there are mostly blue marbles and just a few red ones, you will get a red marble, but it’s not very likely.”
• Activity: Put mostly blue marbles and just a few red marbles in the bag. Tell them, “If we pick a marble, it’s unlikely that we will get a red one.”

Impossible:

• Explanation: “This can’t happen. It’s like if there are no red marbles in the bag at all, you can’t pick a red marble.”
• Activity: Show an empty bag or a bag with only blue marbles and say, “If there are no red marbles, it’s impossible to pick a red one.”

Examples

• Certain: “If we put a red marble in the bag and you pick it, you will get a red marble.”
• Probable: “If there are 7 red marbles and 3 blue marbles, you will probably get a red marble.”
• Unlikely: “If there are 3 red marbles and 7 blue marbles, it’s unlikely you will get a red marble.”
• Impossible: “If there are no red marbles, you can’t get a red one.”

Learn with an example

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